1. Field of the Invention
The present invention relates to a rotary laser apparatus which irradiates plural fan-shaped laser beams under rotation in directions orthogonal to a rotary axis and is used to measure an inclined angle and a height of a site relative to a plane orthogonal to the rotary axis through the irradiated light beams being received with a light-receiving sensor at a position distant from a light-projecting section.
2. Background Technique
Heretofore, there is known a rotary laser apparatus having a construction in which a laser beam source is provided directly on a rotary head (rotation-irradiating section) so as to be rotated relative to an apparatus body (For example, see Patent literature 1: JP-A 2002-527729). According to this apparatus, a cylindrical lens for converting a laser beam from the laser beam source into a fan-shaped laser beam is integrally provided at the rotary head, and the laser beam source and the cylindrical lens are integrally rotated in an identical direction together with the rotary head, so that fan-shaped laser beams are irradiated under rotation.
Further, another rotary laser apparatus is also known in which a laser beam source is provided at an apparatus body (For example, see Patent literature 2: JP-A 2003-214852). According to this apparatus, a laser beam is led to a rotary head along a rotary axis, and biased in a direction orthogonal to the rotary axis. The thus biased laser beam is converted to fan-shaped laser beams with a cylindrical lens or a diffraction lattice, and irradiated under rotation in directions orthogonal to the rotary axis. A reflection mirror, a penta prism or an optical member equivalent thereto is used for biasing the laser beams.
In order to measure an inclined angle and a height of a site with reference to the rotating fan-shaped laser beams, the rotary head must be rotated at a constant and high speed, while the fan-shaped laser beams are not wobbled.
According to the rotary laser apparatus in which the laser beam source and the cylindrical lens are provided directly at the rotary head, the construction of the optical element can be simplified. However, since the apparatus is configured such that the laser beam source is provided directly at the rotary head, deviations of the rotary axis makes direct influences upon the fan-shaped laser beams, so that this unfavorably directly affects detection accuracy of the light-receiving sensor. Furthermore, since an electric power supply mechanism such as a slip ring must be provided in supplying electric power to the laser beam source provided at the rotary head, the electric power-supplying mechanism becomes generally complicated.
On the other hand, according to the rotary laser apparatus in which the laser beam source is provided at the apparatus body, the laser beam is led to the rotary head along the rotary axis, the laser beam is biased in a direction orthogonally to the rotary axis by means of the reflection mirror, the penta prism or the equivalent optical member, the thus biased laser beam is divided into at least two fan laser beams in specified directions, and the divided laser beams are irradiated through the rotary head portion. Since the penta prism or its equivalent optical member has a property of biasing the incident light beam to one orthogonal to the incident direction and emitting it, the rotary axis can be prevented from being wobbled. However, it is not easy to divide the laser beam and rectify the divided laser beams such that each of the laser beams biased in the direction orthogonal to the rotary axis is converted to plural fan-shaped lasers each having a specified shape.